Approximately 196 subjects(1:1 group ratio)will be enrolled. Subjects will receive a single treatment of intramuscular Investigational product up to 360U. The subjects will be observed every 4 weeks until 12 weeks post injection. Outcome measures include Modified Ashworth Scale (MAS), Disability Assessment Scale (DAS), Global Assessment Scale(patient or caregiver/investigator) and Carer burden scale. The primary efficacy endpoint is the change from baseline at week 4 for wrist flexor muscle tone as measured on the Modified Ashworth Scale. Safety parameters will also be measured including adverse events, vital signs and clinical laboratory tests (haematology, serum chemistry and urinanalysis).